Spec Plan — Implementation Planning for Hexagonal Core

Creates structured, ephemeral plan files inside todo/ that track the gap between current code and the desired spec state. Plans are living documents — updated during implementation, then deleted when work is complete.

Important: Plans are ephemeral. Nothing in a plan file should be the only place important decisions are recorded. Decisions belong in specs/. Plans only track the path to get there.

Folder structure

todo/
├── plan.md                            ← project-level index + cross-cutting refactors
├── entities/
│   ├── plan.md                        ← multi-entity work